Metal articles made of, e.g., aluminum, magnesium, titanium, or alloys thereof, with a high-quality mechanical performance have applications in many industries. The articles usually need to be processed to form anodic oxide films via surface treatment process for improving corrosion resistance or abrasion resistance thereof. The anodic oxide films are often subsequently colored to obtain desired decorative appearances. The coloring of the metal articles can be carried out by submersion in a dye solution or otherwise applying a dye thereto. However, during coloring the metal articles, acidic solution used in surface treatment process may flow into holes or slits in the metal articles, and thus cause cloudiness in regions of the anodic oxide film.